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Old 28th September 2004, 02:32 AM   #1
yosh is offline yosh  United States
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Join Date: May 2004
Location: port townsend
Default hummmmmmm?

hello everyone

I am banging my head against a brick wall,knowing that there is a very simple answer to my problem.
Yesterday i bread boarded a very simple 2A3 amp (power supply and 1 channel),everything looked good and when i powered it up it sounded great.today i get home from work with the idea to do the layout for final assembly.so what do i do?i plug it in to hear a bit more while drawing and measuring.The thing sounds terrible,it screams and hisses with the music subtley in the backround.now this is only my second amp but i do remember reading about a test that involves shorting the input jack together,when i do this i calms rite down.the problem is i can't for the life of me remember what that test should tell me.
can anyone help?
thank you
yosh
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Old 28th September 2004, 08:23 AM   #2
Enzo is offline Enzo  United States
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Join Date: Sep 2004
Location: Lansing, Michigan
Just a thought. It sounds like you have a poor ground connection at the input. SO a shielded cable connected there cannot get the benefit of its shield since it doen't get well grounded. How is the input connection grounded? To the chassis or not? If you are relying on the chassis, is the rest of your circuit grounded to it as well? Going from breadboard to chassis might be causing you to make some assumptions that you should not.
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